1. Field of the Invention
The instant invention relates to gear train systems, and more particularly to a high-torque quiet gear for quieting gear train noise over a wide range of applications.
2. Description of the Prior Art
Existing gear trains produce harmonic vibrations which results from the meshing and releasing of gears as they rotate. This vibration frequently produces structural and airborne noise levels which are unacceptable.
Gear noise is presently controlled by designing a gear train system which minimizes the backlash between meshing teeth of a gear train. In addition, various gear teeth configurations have been developed to ensure that more than one tooth is engaged at all times. Close tolerance machining of parts, closely controlling the center to center location of meshing gears, selecting proper materials, controlling system speed of operation, insuring proper system lubrication, limiting piece part loads and isolation of the entire system can also be used to quiet a system.
Another known method of reducing gear backlash is the provision of elastomeric members inserted between the drive shaft and the gear to reduce the transmission of vibration and noise from the drive shaft to the gear or vice-versa. In this regard, the U.S. Patent to Knapp et al., U.S. Pat. No. 4,269,262 is representative of the state of the prior art. The patent to Knapp et al. discloses a gear structure comprising a cylindrical core, an annular ring gear and an elastomeric cushion positioned between the core and the ring gear. Inwardly and outwardly radially projecting portions of the elastomeric cushion are respectively bonded, usually with an adhesive, to the exterior surface of the core and the interior surface of the ring gear.
In general, these types of gear configurations have been found to reduce vibration and noise transmitted from the drive shaft to the gear. However, the gear configurations have a distinct disadvantage in that the bonded area of the elastomer is subjected to high shear forces when torque is transmitted through the system. It has been found that upon repeated use, the bonded surface is highly susceptible to failure, and is the weak link in a multiple piece gear system.
While all of these techniques are partially successful in reducing vibration and noise, they often require expensive manufacturing techniques, and even when combined, have not been found to be fully effective.
It is unlikely that vibrations due to meshing gears can ever be reduced to an undetectable level. The previously noted techniques are all appropriate and applicable, depending on the application and levels of quieting desired for the system being developed. The invention proposed herein is not intended as a complete replacement for these techniques, but rather it is intended to act as a supplement which can be used in conjunction with any of these techniques.